Field of Invention
The present disclosure relates to an electrostatic protection element. More particularly, the present disclosure relates to a gate-bounded silicon controlled rectifier.
Description of Related Art
When sizes of transistors in the integrated circuit (IC) are gradually reduced, an issue is created in which elements may be damaged or destroyed by electrostatic discharge becomes increasingly important. A silicon controlled rectifier (SCR) formed by a parasitic PNP bipolar junction transistor and a parasitic NPN bipolar junction transistor is the most common electrostatic-discharge protection element. With respect to other electrostatic-discharge protection elements, the silicon controlled rectifier has a lower holding voltage, which can afford higher electrostatic-discharge energy in a smaller layout area, but also results in latch up without warning when the silicon controlled rectifier operates in a normal circuit. The integrated circuit may be unable to operate or be destroyed by such latch up.
Accordingly, a significant challenge is related to ways in which to achieve the electrostatic-discharge protection while at the same time avoiding the occurrence of the latch up associated with designing silicon controlled rectifiers.